From f2191f61a7c1ae4ea56ad39dd083d38a826afc9b Mon Sep 17 00:00:00 2001
From: "Yang, Bo" <pop.atry@gmail.com>
Date: Thu, 3 Feb 2022 01:14:42 -0800
Subject: [PATCH] Add Dsl instances for ReaderT

---
 build.sbt                                     |  2 ++
 .../com/thoughtworks/dsl/domains/scalaz.scala | 31 +++++++++++++++++--
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/build.sbt b/build.sbt
index ec5083e7..46079ce2 100644
--- a/build.sbt
+++ b/build.sbt
@@ -190,6 +190,8 @@ lazy val `domains-scalaz` =
       Dsl,
       `macros-Reset` % Test,
       `keywords-Monadic`,
+      `keywords-Get`,
+      `keywords-Put`,
       `keywords-Return`,
       `keywords-TryCatch`,
       `keywords-TryFinally`,
diff --git a/domains-scalaz/src/main/scala/com/thoughtworks/dsl/domains/scalaz.scala b/domains-scalaz/src/main/scala/com/thoughtworks/dsl/domains/scalaz.scala
index e7a84cf9..6384f351 100644
--- a/domains-scalaz/src/main/scala/com/thoughtworks/dsl/domains/scalaz.scala
+++ b/domains-scalaz/src/main/scala/com/thoughtworks/dsl/domains/scalaz.scala
@@ -6,8 +6,16 @@ import com.thoughtworks.dsl.Dsl.!!
 
 import scala.language.higherKinds
 import scala.language.implicitConversions
-import _root_.scalaz.{Applicative, Bind, Monad, MonadError, MonadTrans}
-import com.thoughtworks.dsl.keywords.{Monadic, Return}
+import _root_.scalaz.{
+  Applicative,
+  Bind,
+  Kleisli,
+  Monad,
+  MonadError,
+  MonadTrans,
+  ReaderT
+}
+import com.thoughtworks.dsl.keywords.{Get, Monadic, Put, Return}
 
 import scala.util.control.Exception.Catcher
 import scala.util.control.NonFatal
@@ -206,6 +214,11 @@ object scalaz extends scalaz.LowPriority0 {
     monadTrans.liftM(_)
   }
 
+  // ReaderT/Kleisli's type parameter order does not support partial unification for MonadTrans
+  given [E, F[_], A, B]: Dsl.Lift.OneStep[F[A], Kleisli[F, E, A]] = { fa =>
+    Kleisli(_ => fa)
+  }
+
   /** The [[Dsl]] instance that converts a [[domains.Monadic]] keyword to the
     * monad domain type then flatMap. This instance helps when the keyword
     * supports a domain `D` that can be lifted to the `F[A]`, while there is not
@@ -222,4 +235,18 @@ object scalaz extends scalaz.LowPriority0 {
       )
     }
 
+  given [E, F[_], A]: Dsl.Original[Get[E], ReaderT[E, F, A], E] = Dsl.Original {
+    (keyword, handler) =>
+      ReaderT { e =>
+        handler(e)(e)
+      }
+  }
+
+  given [E, F[_], A]: Dsl.Original[Put[E], ReaderT[E, F, A], Unit] =
+    Dsl.Original { (keyword, handler) =>
+      ReaderT { _ =>
+        handler(())(Put.apply.flip(keyword))
+      }
+    }
+
 }